The recent development of medical technologies has led to the situation where many technologies are used clinically for grafting implants that repair and substitute bones and joints which are defectives or have depleted functions in living bodies such as the human bodies. As to the characteristics required for each of the implants used in these technologies, the implants are desired to have the same strength as part of a living body before being substituted and also, compatibility with a living body, that is, biocompatibility. Examples of biocompatible metallic materials having such characteristics include titanium, titanium alloys, stainless steel and Co—Cr alloys. However, these metallic materials have no living activity so that they are not chemically bonded to a bone, causing problems concerning the occurrences of a gap and loosening during a long time of use.
In light of such problems, there is described in, for example, Japanese Patent Application Laid-Open No. 2008-6164, a method of forming an oxide film in which a hydrogen peroxide-containing paste is brought into contact with the surface of a metal which is a base material to thereby convert the surface of the base material into a metal oxide. According to that disclosure, an oxide film can be formed in a short time and good biocompatibility is obtained.
Further, separately from the above problems, those implants cause the problem that when the implants are grafted in living bodies, infections such as suppuration of diseased parts is caused with high incidence.
To deal with such a problem, there is the idea of using, as implant materials, Cu and Ag that are widely known to exhibit excellent antimicrobial activity. For example, C. N. Kraft, et al., Journal of Biomedical Materials Research Part A, Vol. 49 (1999), Issue 2, pages 192-199 reveals the results obtained by carrying out an experiment in which Ag known to exhibit high antimicrobial activity is transplanted as an implant (made of pure silver) to an animal (hamster). According to these results, it is necessary to cautiously decide whether to use Ag as an implant material because a silver implant causes severer inflammation and swelling as compared with a titanium or stainless steel implant, showing that the silver implant is deteriorated in affinity to a living body.
Further, A. Masse, et al., Journal of Biochemical Materials Research Part B: Applied Biomaterials, Vol. 53 (2000), Issue 5, pages 600-604 reports the result of an experiment concerning inhibition to pin-infections in the case of using an external fixation pin coated with Ag. According to those results, it is not observed that bacterial cells are sufficiently reduced by the Ag coating and it is observed that a rise in Ag level in blood by the grafting of the Ag-coated external fixation pin in a living body.
It could therefore be helpful to provide medical supplies which can inhibit infections with various bacteria for a long period of time, have excellent antimicrobial activity, and are superior in the durability of antimicrobial activity and also superior in biocompatibility, and to provide a method of producing the medical supplies.